05000285/FIN-2013008-32
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Finding | |
|---|---|
| Title | Multiple Examples of Inadequate RISK-BASED Operability Determinations |
| Description | The team identified a non-cited violation of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures and Drawings, involving multiple examples of the licensees use of probability or probabilistic risk assessment when performing operability determinations. The use of probability or probabilistic risk assessment when determining operability is contrary to Procedure NOD-QP-31, Operability Determination Process, Revision 49-53. Specifically, on January 26, 2012 and twice on February 21, 2013, the operability determinations performed for Condition Reports CR 2012-00626, CR 2013-03839, and CR 2013-03842 used probability and/or probabilistic risk assessment to justify the operability of structures, systems, and components. This issue has been entered into the corrective action program as Condition Reports CR 2013-05590, CR 2013-05466, and CR 2013-05597. This performance deficiency is more than minor, and therefore a finding, because it is associated with the equipment performance attribute of the Mitigating Systems Cornerstone, and affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Since the finding involved inadequate operability determinations that occurred while in a shutdown condition and involved plant equipment needed during shutdown conditions, the team used Manual Chapter 0609, Appendix G, Shutdown Operations Significance Determination Process, and determined the finding to have very low safety significance (Green) because the finding did not increase the likelihood of a loss of reactor coolant system inventory, the finding did not degrade the licensees ability to terminate a leak path or add reactor coolant system inventory when needed, and the finding did not degrade the licensees ability to recover decay heat removal once it was lost. This finding has a cross-cutting aspect in the area of human performance associated with the decision-making component because the licensee failed to use conservative assumptions in decision making when performing operability determinations. Specifically, the licensee proposed that a degraded/nonconforming condition was safe by relying on a non-conservative assumption that an event such as a tornado generated missile or external flooding at the site were not likely to occur |
| Site: | Fort Calhoun  |
|---|---|
| Report | IR 05000285/2013008 Section 1R15 |
| Date counted | Jun 30, 2013 (2013Q2) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | A Klett C Smith M Davis J Josey C Bickett G Warnick M Hay J Brand J Groom M Keefe R Latta W Schaup J Watkins B Hagar A Allen J Wingebach K Martin L Wilkins S Morrow R Deese F Ramirez |
| Violation of: | 10 CFR 50 Appendix B Criterion V |
| CCA | H.14, Conservative Bias |
| INPO aspect | DM.2 |
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Finding - Fort Calhoun - IR 05000285/2013008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Fort Calhoun) @ 2013Q2
Self-Identified List (Fort Calhoun)
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